Nail feeding device of nail rolling machine

ABSTRACT

Disclosed is a nail feeding device of a nail rolling machine. Unlike a conventional nail rolling machine in which a finger is used to input (feed) objects to be processed, i.e. nails into a rolling zone defined between a ring dies and a segment dies one by one, thus having low productivity, the nail feeding device includes a worm screw to accurately and rapidly input nails into the rolling zone one by one to ensure successful rolling of the nails, which results in a considerable enhancement in productivity and quality.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a nail feeding device of a nail rolling machine, and more particularly, to a nail feeding device of a nail rolling machine in which a worm screw having a drive device is installed at an entrance of a rolling zone (i.e. a nail rolling zone) and serves to rapidly and accurately input nails, fed from an inclined chute, into the rolling zone, resulting in a considerable enhancement in the productivity and quality of the nail rolling machine.

2. Description of the Related Art

In general, a screw shank nail 5 a as illustrated in FIG. is used in hard woods, and a ring shank nail 5 b as illustrated in FIG. 2 is used in soft woods. The screw shank nail 5 a or the ring shank nail 5 b has been manufactured using a nail rolling machine by forming a plurality of screws (spiral grooves) 5 c or a plurality of rings 5 d on an outer circumferential surface (outer surface) of a nail by a predetermined interval or pitch and thereafter, performing certain post treatments, such as plating, thermal treatment, painting and the like.

Referring to FIGS. 3 to 5 illustrating a conventional nail rolling machine 1, a ring dies 3 is mounted on the center of a base platform 2 via a shaft so as to be rotated by a rotating device or a power transmission device, and a segment dies 4 and a support member 9 to support the segment dies 4 are installed close to a predetermined region of an outer periphery of the ring dies 3. Both the ring dies 3 and the segment dies 4 may be provided at facing surfaces thereof with screw-shaped processing blades 3 a and 4 a in opposite directions respectively as illustrated in FIG. 6. Alternatively, as illustrated in FIG. 7, the ring dies 3 may be provided with ring-shaped processing blades 3 d (the segment dies may be omitted). In this way, a rolling zone 6 is defined between the ring dies 3 and the segment dies 4 such that an object to be processed, i.e. a nail 5 is rolled while being moved and rotated along the rolling zone 6.

Accordingly, if the nail 5 slides down along an inclined chute 7 and is introduced into an entrance 6 a of the rolling zone 6 by means of a finger 8, the nail 5 is rolled while being moved and rotated along the rolling zone 6 via rotation of the ring dies 3 and after completion of rolling, is discharged from an exit 6 b. The resulting nail 5 may be provided at an outer circumferential surface thereof with the plurality of screws 5 c or the plurality of rings 5 d by the processing blades formed respectively at the facing surfaces of the ring dies 3 and the segment dies 4.

In the case in which grooves 3 b and 4 b are respectively formed at partial portions of the ring dies 3 and the segment dies 4 (in other words, the processing blades 3 a, 4 a and 3 d are not formed at the partial portions), the resulting nails are not provided at partial portions thereof with the screws 5 c or the rings 5 d, like the nails 5 a and 5 b as illustrated in the right side of FIGS. 1 and 2.

In the above described conventional nail rolling machine 1, the ring dies 3 and the segment dies 4 have a predetermined radius of curvature and therefore, the nail 5 is continuously oriented in an upright position while passing through the rolling zone 6. Additionally, a finger drive device is installed at a lateral portion of the ring dies 3 to allow the finger 8 to input the nails 5 fed from the inclined chute 7 into the entrance 6 a of the rolling zone 6 one by one.

The finger drive device includes a cam 10 which is placed above the ring dies 3 so as to be rotated along with the ring dies 3, a wheel 11 which comes into contact with an outer surface of the cam 10, the finger 8 which is operated to input the nails 5 in a direction designated by the arrow A one by one, an actuating member 13 to which the finger 8 and the wheel 11 are secured, a shaft 12 which is coupled to the actuating member 13, and an elastic support member 14 which acts to push the actuating member 13 so as to cause the wheel 11 to come into contact with the cam 10. A stopper 15 is installed at the entrance 6 a of the rolling zone 6 and is adapted to be moved forward or backward as designated by the arrow of FIG. 4. The stopper 15 serves not only to keep the nail 5 introduced into the rolling zone 6 vertical, but also to prevent the introduced nail 5 from moving backward.

The rolling zone 6 needs a function of adjusting a distance (gap) according to a diameter of the nail 5. To this end, a fixing member 18, which is located at one end of the support member 9 of the segment dies 4, is provided with a gap regulator 16 and a pair of balancers 17, which serve to adjust the size of the rolling zone 6, i.e. a distance between the ring dies 3 and the segment dies 4.

The cam 10 is provided with a plurality of valleys 10 a and peaks 10 b alternately arranged throughout an outer circumferential surface thereof. When the wheel 11 is located at the top of any one peak 10 b as illustrated in FIG. 3, the finger 8 is in a backwardly moved state. When the wheel 11 is located in any one valley 10 a, the finger 8 is moved forward in a direction designated by the arrow A, acting to push the nail 5 into the entrance 6 a of the rolling zone 6. The introduced nail 5 is rolled while passing through the rolling zone 6 by rotational power of the ring dies 3, thereby being processed into the screw shank nail 5 a as illustrated in FIG. 1 or the ring shank nail 5 b as illustrated in FIG. 2.

Due to the fact that the finger 8 has low productivity and reliability, the above described conventional nail rolling machine 1 has several problems in that excessive operating noise occurs when the nail 5 is introduced into the rolling zone 6 and in that the nail 5 may fail to be accurately introduced into the entrance 6 a due to shock, vibration and the like. Moreover, high speed operation may shorten the lifespan of the finger 8. When replacing the finger 8, which seems no longer of any use, with a new finger, setting the new finger to perform a normal operation may require considerable time, up to several hours, which results in a considerable deterioration in productivity. In addition, even the stopper 15 may exhibit several problems, such as frequently preventing the nail 5 from entering the rolling zone 6.

Document Considered to be Relevant

There are Patent documents, such as, Korean Utility Model Registration No. 20-0001423 (published on Aug. 26, 1979) entitled “Nail Making Machine”, Korean Utility Model Registration No. 20-0240588 (published on Sep. 26, 2001) entitled “Apparatus for Manufacturing Round Cap Nail”, and Korean Patent Registration No. 10-0675344 (published on Jan. 30, 2007) entitled “Apparatus for Successively Manufacturing Tacker Nail”.

SUMMARY OF THE INVENTION

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a nail feeding device of a nail rolling machine in which a worm screw (or a ball screw) having a drive device is provided to ensure that nails are rapidly and accurately input into a rolling zone one by one for the sake of successful rolling thereof.

It is another object of the present invention to provide a nail feeding device of a nail rolling machine in which a nail guide member is installed below a worm screw to assist nails in being sequentially introduced into a rolling zone in a vertically aligned state without a risk that lower ends of the nails cross each other.

It is a further object of the present invention to provide a nail feeding device of a nail rolling machine in which a lifting restrainer is installed to an inclined chute at a position above the worm screw so as to prevent heads of nails from being lifted.

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a nail feeding device of a nail rolling machine in which a worm screw (or a ball screw), which is easy to set and has high productivity and reliability, is installed at an entrance of a rolling zone to rapidly and accurately input nails, fed from an inclined chute, into the rolling zone, thereby achieving a considerable enhancement in productivity and quality.

The worm screw may have a drive device associated with a controller. Also, the worm screw may be provided throughout an outer surface (i.e. an outer circumferential surface) thereof with a spiral protruding ridge and a spiral groove arranged by a predetermined interval or pitch, so as to assist the nails in being accurately moved into the rolling zone. In addition to the controller, an RPM sensing device may be provided to sense revolutions per minute of the worm screw and input the sensed result to the controller, so as to ensure that the rate of rotation (or the rotating speed) of the worm screw is precisely controlled.

A lifting restrainer may be installed to the inclined chute at a position above the worm screw and serve to prevent heads of the nails from being lifted.

The spiral protruding ridge and the spiral groove of the worm screw may be formed in a direction to move and input the nails to the entrance of the rolling zone. The worm screw may have a vertical tip end surface to prevent backward movement of the nails introduced into the rolling zone, which makes it unnecessary to provide a stopper and ensures that the nails are kept vertical.

A nail guide member may be installed below the worm screw to assist the nails in being sequentially introduced into the rolling zone while being kept in a vertically aligned state without a risk that lower ends of the nails cross each other.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a front view of a rolled nail with a screw shank;

FIG. 2 is a front view of a rolled nail with a ring shank;

FIG. 3 is a reference view illustrating operation of a conventional nail rolling machine;

FIG. 4 is a plan view illustrating a cam part of the conventional nail rolling machine;

FIG. 5 is a reference view of the cam part of the conventional nail rolling machine;

FIG. 6 is a perspective view illustrating external appearances of a ring dies and a segment dies, which are provided with screw-shaped blades;

FIG. 7 is a perspective view illustrating an external appearance of a ring dies provided with ring-shaped blades;

FIG. 8 is a perspective view illustrating an external appearance of a nail rolling machine according to an exemplary embodiment of the present invention;

FIG. 9 is a plan view illustrating important parts of the nail rolling machine according to the exemplary embodiment of the present invention;

FIG. 10 is a perspective view illustrating an external appearance of a worm screw according to an exemplary embodiment of the present invention;

FIG. 11 is a side view of the worm screw according to the exemplary embodiment of the present invention;

FIG. 12 is a side view illustrating a state in which nails are introduced into a rolling zone according to the present invention;

FIG. 13 is a plan view illustrating the state in which the nails are introduced into the rolling zone according to the present invention;

FIG. 14 is a perspective view illustrating a guide member according to an exemplary embodiment of the present invention;

FIG. 15 is a perspective view illustrating an installed state of the guide member according to the exemplary embodiment of the present invention; and

FIG. 16 is a circuit block diagram according to an exemplary embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, the same or similar elements are denoted by the same reference numerals even though they are depicted in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 8 is a perspective view illustrating an external appearance of a nail feeding device of a nail rolling machine 20 according to the present invention, FIG. 9 is a plan view illustrating important parts of the present invention, FIG. 10 is a perspective view illustrating an external appearance of a worm screw 22, and FIG. 11 is a side view of the worm screw 22.

The nail feeding device of the nail rolling machine 20 according to the present invention basically includes the ring dies 3 adapted to be rotated by a drive device, the segment dies 4 and the segment dies support member 9 coupled to one side of the ring dies 3 so as to face each other, the rolling zone 6 defined between the ring dies 3 and the segment dies 4, the inclined chute 7 extending to the entrance 6 a of the rolling zone 6, and the gap regulator 16, the balancers 17 and the fixing member 18 which serve to adjust a distance (or gap) of the rolling zone 6 according to the diameter of the nails 5, similar to the previously described conventional nail rolling machine 1. The present invention has a feature in that a worm screw 22 having a drive device is installed at the entrance 6 a of the rolling zone 6, which ensures that the nails 5 can be accurately and rapidly introduced into the rolling zone 6 one by one and then, discharged from the rolling zone 6 after completion of rolling. The worm screw 22 is provided throughout an outer circumferential surface 22 d thereof with a spiral protruding ridge 22 a and a spiral groove 22 b in such a way that the spiral protruding ridge 22 a and the spiral groove 22 b alternate with each other by a predetermined interval or pitch, so as to assist the nails 5 in entering the rolling zone 6 at a constant speed.

The drive device of the worm screw 22, as illustrated in FIG. 13, includes a timing pulley 34 secured to a shaft 19 of the worm screw 22, a timing pulley 28 secured to a rotating shaft of a motor 26, a timing belt 36 to connect the timing pulleys 28 and 34 to each other, and an anti-overload mechanism coupled to the timing pulley 28. The drive device serves to transmit rotational power to the worm screw 22.

The anti-overload mechanism, which is coupled to the timing pulley 28, includes a lining 31 which comes into contact with one surface of the timing pulley 28, a shoe 32 connected to the rotating shaft of the motor 26, an additional lining 33 which comes into contact with the other surface of the timing pulley 28, a shoe 35 which comes into contact with the lining 33, and an elastic spring 37 accommodated in a spring housing 39 to elastically support the shoe 35.

Through provision of the worm screw 22, in the case in which the nails 5 are not introduced, or overload is applied to the worm screw 22 due to introduction of defective nails and the like, the timing pulley 28 may perform a slip motion to prevent transmission of rotational power to the worm screw 22 even if the motor 26 is continuously rotated. This may prevent breakage or damage to main components, such as the worm screw 22, the inclined chute 7, the ring dies 3, the segment dies 4 and the like.

The nails 5, fed to the inclined chute 7, are adapted to slide down in an evenly linearly aligned state along a guide slot of the inclined chute 7. However, in the case in which new nails 5 are fed to the inclined chute 7 in a state in which all or almost all of the nails 5 fed to the inclined chute 7 were used, some of the nails 5 sliding down along the guide slot may collide with stationary nails, which may cause the nails 5 to be separated from the inclined chute 7 or heads of the nails 5 to be lifted and overlap each other. Consequently, accurate feeding of the nails 5 may be impossible.

To solve the above described problem, according to the present invention, as illustrated in FIG. 12, the inclined chute 7 is provided at a position thereof above the worm screw 22 with a lifting restrainer 38 to prevent lifting of the heads of the nails 5. A rear end of the lifting restrainer 38 is connected to another lifting restrainer 40 by means of a shaft pin 42, and a front end of the lifting restrainer 38 is provided with a handle 44. The handle 44 can be manually lifted about the shaft pin 42 when it is desired to correctly align misaligned nails or to remove defective nails. A spring 46 is installed to a middle portion of the lifting restrainer 38 and serves to force the lifting restrainer 40 such that the lifting restrainer 40 is elastically supported downward onto an upper surface of the inclined chute 7.

In the present invention, if the worm screw 22 is rotated by the drive device, the nail 5 fed from the inclined chute 7 is first moved forward along the spiral groove 22 b and then, is accurately and rapidly introduced into the entrance 6 a of the rolling zone 6. The nail 5 having passed through the entrance 6 a is moved toward the exit 6 b of the rolling zone 6 while being rotated along with the ring dies 3 via rotation of the ring dies 3. Thereby, the nail 5 is rolled under cooperation between the ring dies 3 and the segment dies 4 and after completion of rolling, is discharged from the exit 6 b. In the present invention, the worm screw 22 has a vertical tip end surface 22 c to prevent the nail 5 introduced into the rolling zone 6 from moving backward, which enables elimination of a stopper that has conventionally been provided to prevent backward movement of the nail 5.

A controller 24 is provided to control a rotating speed of the motor 26. The worm screw 22 is rotated in a given direction to move an object to be processed, i.e. the nail 5 forward toward the entrance 6 a. Specifically, a rotating direction of the worm screw 22 is changeable according to a winding direction of the spiral protruding ridge 22 a and the spiral groove 22 b formed at the worm screw 22 (i.e. a clockwise direction or a counterclockwise direction).

An RPM sensing device is provided to sense revolutions per minute (RPM) of the worm screw 22 and input the sensed result to the controller 24, which enables control of the rate of rotation of the worm screw 22. Specifically, a sensing object 50 is installed at a position where the sensing object 50 does not interfere with movement of the nail 5, for example, at one end of the shaft 19 of the worm screw 22 or at one end of the timing pulley 34 as illustrated in FIG. 13, so as to be rotated along with the timing pulley 34, and a proximity sensor 52 is installed in the vicinity of the sensing object 50 so as to sense access of the sensing object 50. The proximity sensor is connected to an input side of the controller 24. Accordingly, as the proximity sensor 52 senses the rate of rotation of the worm screw 22 and inputs a sensed RPM value to the controller 24, the controller 24 can control the rate of rotation (or the rotating speed) of the worm screw 22 to a preset value by comparing a reference RPM value, which is set by a setting unit, with the sensed RPM value input from the proximity sensor 52.

Although the spiral protruding ridge 22 a formed at the worm screw 22 according to the present invention has an inclined surface, the nail 5 is kept vertical when introduced into the entrance 6 a since the tip end surface (or a distal end surface) 22 c of the worm screw 22 is a vertical surface as illustrated in FIGS. 10 and 11 and is located close to a lateral surface of the segment dies 4 so as not to come into contact with the lateral surface. Thus, the worm screw 22 prevents the nail 5 introduced into the rolling zone 6 from being deflected downward (sagging) or being deflected upward (lifting) while passing through the rolling zone 6 by a processing pressure.

In the present invention, when moved forward along the spiral groove 22 b, the nail 5 is centrally supported by the spiral groove 22 b.

In the present invention, for the sake of smooth introduction of the nail 5, an air injection nozzle 54 may be installed at the entrance 6 a of the rolling zone 6 as illustrated in FIG. 13, FIG. 16 is a circuit block diagram according to an exemplary embodiment of the present invention. The air injection nozzle 54 is provided with an air pressure source 56 and an opening/closing valve 58.

Although an injection pressure of the air injection nozzle 54 is variable according to the size or type of the nails 5 and a rolling environment, it is preferable that the injection pressure be in the range of 1 kg/cm² to 5 kg/cm². The air injection nozzle 54 is installed in an angle adjustable manner, such that an injection direction thereof can be adjusted according to the size or length of the nails 5. The air injection nozzle 54 is preferably installed to face the entrance 6 a of the rolling zone 6 and an air injection position of the air injection nozzle 54 is preferably slightly higher than the center of the length of the nail 5.

The nail 5, which is moved along the rolling zone 6 via rotation of the ring dies 3, is kept vertical during rolling as well as when discharged from the rolling zone 6 owing to a predetermined radius of curvature of the ring dies 3 and the segment dies 4. As illustrated in FIGS. 1 and 2, the discharged nail 5 is provided at the outer circumferential surface thereof with the plurality of screws 5 c or the plurality of rings 5 d. Then, the resulting rolled nail 5 may be additionally subjected to post treatments, such as plating, thermal treatment, painting and the like to thereby be applicable for various purposes.

For example, the nail 5 a provided with the screws 5 c as illustrated in FIG. 1 is applicable to hard woods, and the nail 5 b provided with the rings 5 d as illustrated in FIG. 2 is applicable to soft woods. Here, it will be appreciated that the screws 5 c or the rings 5 d obtained by rolling are given by way of example for convenience of explanation and of course, various other appropriate shapes of grooves may be adopted.

FIG. 14 is a perspective view illustrating a guide member according to an exemplary embodiment of the present invention, and FIG. 15 is a perspective view illustrating an installed state of the guide member 60. The guide member 60 is installed below the worm screw 22 and serves to assist the nails 5 in being sequentially introduced into the rolling zone 6 by the worm screw 22 while being kept in a vertically aligned state (or by a constant interval) without a risk that lower ends of the nails 5 cross each other.

The guide member 60 includes a fixing portion 62 fastened to a block 78 using a bolt 74, a through-hole 64 perforated in the fixing portion 62 for penetration of the bolt 74, a horizontal portion 66 formed at the top of the fixing portion 62, a connecting portion 68 formed at a distal end of the horizontal portion 66, a planar portion 72 formed at an outer surface of the connecting portion 68 to assist the nails 5 in being aligned when introduced into the rolling zone 6 by the worm screw 22, and a recess 70 indented in an upper surface of the connecting portion 68 so as to be located close to the worm screw 22.

The guide member 60 is secured to the block 78 as the bolt 78 is fastened into the through-hole 64. A shaft support portion 80 of the worm screw 22 is also bolted to the block 78. As a horizontal protrusion formed at the guide member 60 is fitted into a horizontal groove 76 formed at the block 78, the guide member 60 can be immovably fixed.

The planar portion 72 of the guide member 60 extends parallel to a longitudinal direction of the worm screw 22, and the recess 70 indented in the upper surface of the guide member 60 is located close to the worm screw 22 so as not to come into contact with the worm screw 22. This configuration may prevent friction between the guide member 60 and the worm screw 22 as well as unnecessary movement of the nail 5.

Unlike conventional rolling machines which have a risk of unwanted stoppage due to overload applied thereto when the lower ends of the nails 5 cross or overlap each other due to impurities adhered to surfaces of the nails, air current and the like, according to the present invention, the nails 5 can be aligned by coming into contact with the planar portion 72 of the guide member 60 when introduced into the rolling zone 6 by the worm screw 22, which prevents the lower ends of the nails 5 from crossing or overlapping each other and consequently, prevents overload from being applied to the nails 5 upon introduction.

According to the present invention, by using the worm screw 22 (or a ball screw) having the controller 24 and the drive device instead of the finger 8 and the finger drive device that have been conventionally used to input the nail 5 into the entrance 6 a of the rolling zone 6, a considerable enhancement in the productivity and quality of the rolled nails 5 a and 5 b can be accomplished.

Comparing productivity, the previously described conventional nail rolling machine 1, which is configured to input the nail 5 using the finger 8, processes about 1200 nails per minute, whereas the nail rolling machine 20 of the present invention, which is configured to input the nail 5 using the worm screw 22, can process about 3000 nails per minute. Of course, when the rotating speed of the worm screw 22 is further enhanced by the controller 24, productivity can be further enhanced without deterioration in quality.

In the drawings, reference numeral 3 c designates a hollow of the ring dies 3, reference numeral 21 designates a nail feeding vessel, reference numeral 23 designates a chute to discharge rolled nails, reference numeral 22 a designates a shaft hole of the worm screw 22, and reference numeral 22 f designates a screw hole to fix the worm screw 22.

As is apparent from the above description, the present invention provides a nail feeding device of a nail rolling machine in which a worm screw serves to rapidly and accurately input (feed) nails, fed from an inclined chute, into a rolling zone one by one, which results in a considerable enhancement in the productivity and rolling quality of the nail rolling machine.

Further, the nail rolling machine according to the present invention has a simplified configuration and is easy to set after installation.

Furthermore, according to the present invention, a lifting restrainer is installed to the inclined chute at a position above the worm screw, which can prevent heads of nails from being lifted.

In addition, according to the present invention, a nail guide member is installed below the worm screw and serves to assist the nails in being sequentially introduced, in a vertically aligned state, into the rolling zone without a risk that lower ends of the nails cross each other.

Although the exemplary embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 

1. A nail feeding device of a nail rolling machine, comprising: a ring dies; a segment dies; a segment dies support member; a rolling zone defined between the ring dies and the segment dies; an inclined chute extending to an entrance of the rolling zone; and a gap regulator to adjust a distance between the ring dies and the segment dies, wherein a worm screw having a drive device is installed between the inclined chute and the entrance of the rolling zone, whereby a nail, fed from the inclined chute, is moved forward in a vertically aligned state while being caught at a head thereof by a spiral protruding ridge of the worm screw to thereby be sequentially introduced into the entrance of the rolling zone.
 2. The nail feeding device according to claim 1, wherein the worm screw includes a vertical tip end surface.
 3. The nail feeding device according to claim 1, wherein an air injection nozzle, having an air pressure source and an opening/closing valve, is installed at the entrance of the rolling zone.
 4. The nail feeding device according to claim 1, wherein the drive device of the worm screw includes: timing pulleys secured respectively to a shaft of the worm screw and a rotating shaft of a motor that is controlled by a controller; a timing belt installed to connect the timing pulleys to each other so as to rotate the worm screw in a given direction to move and input the nail into the rolling zone; a sensing object secured to one end of the timing pulley; a proximity sensor located in the vicinity of the sensing object and serving to sense access of the sensing object, wherein the proximity sensor is connected to an input side of the controller having a setting unit.
 5. The nail feeding device according to claim 1, wherein a guide member, provided with a planar portion, is installed below the worm screw and serves to assist nails in being sequentially introduced into the rolling zone by the worm screw in a state in which lower ends of the nails are aligned.
 6. The nail feeding device according to claim 5, wherein the guide member includes: a fixing portion having a through-hole; a horizontal portion formed at the top of the fixing portion; a connecting portion formed at a distal end of the horizontal portion; the planar portion formed at an outer surface of the connecting portion to assist the nails in being aligned when introduced into the rolling zone by the worm screw; and a recess indented in an upper surface of the connecting portion so as to be located close to the worm screw.
 7. The nail feeding device according to claim 1, further comprising a lifting restrainer installed to the inclined chute at a position above the worm screw so as to prevent the head of the nail 5 from being lifted.
 8. The nail feeding device according to claim 7, wherein the lifting restrainer includes: a shaft pin to connect a rear end of the lifting restrainer to an additional lifting restrainer; a handle provided at a front end of the lifting restrainer and adapted to be manually lifted about the shaft pin so as to correctly align misaligned nails or to remove defective nails; and a spring installed to a middle portion of the lifting restrainer to allow the additional lifting restrainer to be elastically supported downward onto an upper surface of the inclined chute so as to prevent the head of the nail from being lifted. 